Pool and tank cleaners of the prior art generally operate in a random pattern of movement across the bottom of the pool or tank. The forward or advancing end of the cleaner can either be stopped and reversed at the sidewall of the pool, or be designed to climb the sidewall until the leading edge of the advancing end is at the waterline, after which the cleaner reorients itself and descends the sidewall and moves across the bottom of the pool along a different line of travel. By criss-crossing the pool for a sufficient period of time and along a sufficient number of varied paths, all, or substantially all, of the bottom of the pool is by the passing cleaner.
In very large rectangular pools, e.g., Olympic-sized pools maintained by educational institutions, water parks and municipalities, a substantial amount of time is required to assure that the cleaner following a random pattern will clean the entire bottom surface of the pool. It can arise that the cleaning cycle is longer than the time that can be allotted for this maintenance activity.
One solution that has been offered to expedite the cleaning of the pool is to join two or even three individual pool cleaners into a unitary parallel assembly in order to cover a path that is twice the width (for the double assembly) as would be covered by a single moving cleaner. This cleaner is also designed to operate in a random pattern. However, there are difficulties associated with the handling, transportation, storage and control of these double (or larger) units that present drawbacks to their use. These oversized units are heavy and can be difficult to remove from the pool due to their bulk and weight. The floating power cord is also necessarily long and heavy and subject to twisting and can interfere with the programmed pattern of the cleaner.
Another solution that has been developed for producing a more or less predictable scanning pattern by a pool cleaner is a gyroscopically controlled guidance system. This system is expensive to construct and must also be oriented at a prescribed starting point. Thereafter the unit follows a series of straight lines, the drive motors being controlled by the gyroscope, which result in a zig-zag pattern. The principal drawback is the cost of the unit.
It is therefore an object of this invention to provide a method and apparatus for controlling the direction and pattern of a pool cleaner across the bottom of a pool or tank in order to minimize the time required to clean the entire bottom surface of the pool.
It is another object of this invention to provide a pool cleaner that follows a regular geometric pattern that is parallel to the sidewalls of a rectilinear pool, and also a pattern in which subsequent paths traversing the area between the sidewalls are not only parallel, but also closely spaced to each other.
Yet another object of the invention is to provide a method and apparatus in which the pool cleaner first traverses a plurality of parallel paths from side to side, and then when it reaches an end wall, turns and begins traversing a plurality of parallel, closely-spaced paths that extend from one end of the pool to the other.
Another object of the invention is to provide a method an apparatus for controlling the movement of a robotic pool cleaner so that the cleaner's regular pattern is not interrupted or adversely affected by its encounters with the corners or other obstructions in or along the side walls of the pool being cleaned.
A still further object of the invention is to provide a robotic pool cleaner that is programmed to clean a rectilinear pool or tank in the most efficient manner possible, and to thereby reduce operating and maintenance expenses.
Yet another object of the invention is to provide a robotic pool cleaner that follows a regular geometric pattern and whose motion is controlled so that the power supply cord does not interfere with the intended pattern due to a twisting or coiling of the cord.
It is yet another object of the invention to provide a pool cleaner that can accomplish the above objects at a cost that is relatively less expensive than the prior art gyroscopically-controlled cleaners.